Served
at age 13 as a militia messenger during the Revolutionary War; was captured,
becoming the only President to have been held as a prisoner of war (Washington had surrendered
in the French and Indian War but was immediately paroled); served
in the War of 1812, attaining the rank
of major general and became a national hero after his success at
the Battle of New
Orleans.

No, but served between 1775-1781 during the Revolutionary War. Also see
Service Notes.

Left militia to enter Virginia legislature. (Some sources claim
Madison briefly assumed command of an artillery battery during the
British assault on Washington during the War
of 1812. If true, he would join Washington (Whiskey Rebellion)
as having seen military service as commander-in-chief.)

He attempted to join the Navy during the Spanish American War but was unable as
he contracted measles. Served as Assistant
Secretary of the Navy from
1913 and through World War I; when the
U.S. entered the war in 1917 he offered his resignation so that he
could apply for a commission in the Navy, but was refused by the
President. Witnessed fighting in World War I. In a post World War I
publication "Harvard in the War" he is listed among the Harvard's
contributors to World War I effort. He served as President during
World War II.